Systems, methods and devices for removing obstructions from a blood vessel

ABSTRACT

Devices and methods for removing an obstruction from a blood vessel are described. The devices are deployed in a collapsed condition and are then expanded within the body. The devices are then manipulated to engage and remove the obstruction.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of application Ser. No.11/046,532, filed Jan. 28, 2005 now U.S. Pat. No. 7,727,242, which is acontinuation-in-part of application Ser. No. 10/839,977, filed May 5,2004 now U.S. Pat. No. 7,766,921, which is a continuation-in-part ofapplication Ser. No. 10/460,751, filed Jun. 11, 2003 now abandoned,which is a continuation-in-part of application Ser. No. 10/055,714,filed Jan. 22, 2002 now U.S. Pat. No. 7,285,126, which is acontinuation-in-part of application Ser. No. 09/891,141, filed Jun. 25,2001 now U.S. Pat. No. 6,824,545, which is a continuation in part ofapplication Ser. No. 09/756,476, filed Jan. 8, 2001 now U.S. Pat. No.6,663,650, which is a continuation-in-part of application Ser. No.09/605,143, filed Jun. 29, 2000 now U.S. Pat. No. 6,730,104, the fulldisclosures of which are incorporated herein by reference for allpurposes.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention is directed to methods and devices for removingobstructions from blood vessels. The device may be used to retrieve andremove clots and other biological obstructions. The device may also beused to retrieve embolic coils and the like which have been misplaced orhave migrated to an undesirable location.

One such obstruction removal device is disclosed in U.S. Pat. No.5,895,398 which is hereby incorporated by reference. The device has anexpandable engaging member which is introduced into the blood vessel toengage the obstruction for removal.

The present invention is also directed to devices, systems and methodswhich use an expandable capture element when removing obstructions froma blood vessel. One such system for removing obstructions in a bloodvessel is described in U.S. Pat. No. 5,102,415 to Guenther et al. Thesystem described in U.S. Pat. No. 5,102,415 has a balloon catheter and acatheter having an expandable tip which receives the obstruction. Theballoon catheter is passed through the obstruction while the balloon isdeflated. The balloon is then inflated and the tip of the catheter isexpanded. The balloon is then moved proximally so that the obstructionis pulled into the expanded tip of the catheter. A problem with thesystem of U.S. Pat. No. 5,102,415 is that the interaction between theballoon catheter and the leading edge of the catheter may tend to shearoff portions of the obstruction. This can cause obvious problems whenworking in sensitive vascular areas.

The present invention is directed to additional devices and methods forremoving obstructions in a blood vessel.

SUMMARY OF THE INVENTION

In accordance with the present invention, device and methods forremoving obstructions are provided. In a first aspect of the invention,an obstruction removal device is provided which has an obstructionengaging element extending from an insertion element. The engagingelement is movable from a collapsed position to an expanded position.The engaging element forms coils having varying diameter wherein thecoils at a distal portion are larger than coils at an intermediateportion. The distal portion forms a relatively closed structure whichprevents the obstruction, or any part thereof, from migratingdownstream. The distal portion is expanded distal to the obstructionwhile the proximal portion engages and holds the obstruction.

In another aspect of the present invention, another obstruction removaldevice is provided which has at least one closed loop and preferably twoclosed loops. The closed loop provides an advantage when advancedthrough a catheter or sheath in that the closed loop produces opposingradial forces on the catheter or sheath through which the loop isadvanced. In this manner, the obstruction removal device can be advancedmore easily through the catheter or sheath to prevent binding or kinkingof the device during advancement. In a preferred embodiment, theobstruction removal device has two loops of varying diameter with thedistal loop having a larger diameter. Each of the loops lie in a planewith the planes of the two loops preferably being perpendicular to oneanother.

Any of the obstruction removal devices described herein may also be usedwith a source of power coupled to the obstruction removal device for useas described below. The source of power may simply produce a positive ornegative charge or may be an RF energy source. The source of power maybe used to help the obstruction removal device penetrate and engage theobstruction and may also be used to adhere the obstruction to theobstruction removal device as will be described. In a preferredembodiment, a negative charge is provided when advancing the obstructionremoval device into the obstruction and a positive charge, or RF energy,is supplied to adhere the device to the obstruction.

In another aspect of the present invention, the obstruction removaldevice has a core element surrounded by a sheath. A strand, preferablyabout four strands, are positioned between the core element and thetube. The strand and the tube prevent any part of the obstructionremoval device from breaking free should the core element fail. Thestrand and tube will hold the obstruction removal device together evenif the core element breaks. The sheath is preferably flexible so thatthe sheath can undergo much larger deflections than the core element.

The obstruction removal devices of the present invention may also beadvanced through a guide catheter having a flow restricting elementwhich is preferably a balloon but may be any other suitable structure.The flow restricting element is expanded to reduce blood flow throughthe obstructed vessel to minimize the likelihood that the obstructionwill migrate downstream.

In another aspect of the invention, a system is provided which has anexpandable capture element and an obstruction engaging device whichtogether work to remove an obstruction from a blood vessel. The captureelement is advanced through the patient in a collapsed position and isexpanded when at the desired location. The obstruction engaging devicepreferably has one or more filaments which provide a relatively flexibleinteraction between the engaging device and the capture element. Thisprovides advantages over the use of a balloon catheter as described ingreater detail below. The obstruction engaging device preferably has 1-4filaments and more preferably 1-2 filaments. Of course, the obstructionengaging device may have more filaments without departing from variousaspects of the invention and, in fact, the device may form a filterwhich further helps to prevent portions of the obstruction from beingcarried downstream.

The capture element is preferably naturally biased toward the expandedposition although the capture element may also be manually actuated asdescribed below. The capture element has a support structure with aflexible cover attached thereto. The support structure preferably has aclosed loop which opens the distal end of the cover. The loop ispreferably integrally formed and has a number of integrally formedhinges which deflect when the loop is expanded and collapsed. The hingesare preferably V-shaped although other shapes may be used. A pluralityof struts extend proximally from the loop.

The capture element may also be expanded by the user so that the usermay select the appropriate time for expansion of the capture element. Inthis manner, the user may advance the capture element to a suitablelocation for expansion. The user may also collapse the capture elementbefore withdrawing the capture element into a catheter. The captureelement has an actuator for opening and closing the capture element. Theactuator may have a control arm and a stable arm although any suitableactuator may be used. The control arm is manipulated to expand andcontract a loop at the distal end of the capture element. Alternatively,the actuator may be a tube which cinches the loop closed. In a specificembodiment, the capture element may also evert when moving to theexpanded position.

The device of the present invention may be used in various differentlocations and for various different purposes. In one embodiment, thedevice may be used in connection with a guide catheter. When used withthe guide catheter, the device may be expanded to slow or even stopblood flow when performing other procedures downstream of the guidecatheter such as removing a clot or placing a stent.

Alternatively, the device may be passed through a conventional guidecatheter so that the device may be introduced further into thevasculature. In this system, the capture element passes through theguide catheter. The obstruction engaging device is then used to engagethe obstruction and move the obstruction into the capture element.

In still another aspect of the invention, the capture element invertswhen the obstruction is moved into the capture element. The obstructionis preferably engaged with an engaging element having a filament whichensnares the obstruction. The obstruction engaging element may beindependent from the capture element or may be connected to the engagingelement. The capture element inverts upon application of a compressiveforce to the inverting portion or upon any other suitable actuationforce. The capture element preferably inverts when the compressive forceis applied by either the obstruction or the engaging element.

In still another aspect of the present invention, a device and methodfor removing an obstruction from a blood vessel is provided. A strandextends along the elongate obstruction removing element and extendsbetween the coils of the element. The element may be manipulated toentangle the main element with the strand and to entangle the devicewith the obstruction. The strand will become entangled with the elementat locations dependent upon permitted expansion of the element withinthe blood vessel.

In yet another aspect, an intravascular device and method for removingmaterial from a vascular site are provided. A filament is wrapped aroundthe main element in a delivery condition. The filament and main elementare then rotated relative to one another to cause the two to essentiallyunravel.

In another aspect of the present invention, the obstruction removingelement has a proximal end slidably coupled to an insertion element anda distal end attached near the distal end of the insertion element.Distal displacement of a proximal portion of the obstruction removingelement is limited relative to the insertion element to preventexcessive distortion of the obstruction removing element. The insertionelement may have a stop which engages the proximal portion of theelement or one or more filaments may be provided between the obstructionengaging element and the insertion element. The filaments may beslidably coupled to the expandable portion of the obstruction removingelement to permit the device to conform somewhat to the region where thedevice is being deployed.

These and other advantages of the invention will become apparent fromthe following description, drawings and claims.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 shows a system for removing an obstruction.

FIG. 2 shows the obstruction removal device in a collapsed condition.

FIG. 3 shows the obstruction removal device with a distal portion of theobstruction removal device expanded.

FIG. 4 shows the obstruction removal device with a proximal portionexpanded to engage an obstruction.

FIG. 5 shows the capture element collapsed around the obstruction priorto withdrawal.

FIG. 6 shows the capture element contained within the catheter in aninverted position when collapsed.

FIG. 7 shows another device for capturing an obstruction.

FIG. 8 shows the capture device of FIG. 7 advanced at least partiallyinto engagement with the obstruction.

FIG. 9 shows an obstruction engaging element advanced through thecapture element.

FIG. 10 shows the element engaging the obstruction.

FIG. 11 shows the obstruction partially contained within the captureelement.

FIG. 12 shows the obstruction completely contained within an invertedportion of the capture element.

FIG. 13 shows still another device for capturing an obstruction.

FIG. 14 shows the element engaging the obstruction.

FIG. 15 shows the inverting portion beginning to invert to capture theobstruction.

FIG. 16 shows the obstruction partially contained within the captureelement.

FIG. 17 shows the obstruction completely contained within the captureelement.

FIG. 18 shows the inverting portion contained within another cathetersuch as the guide catheter for removal from the patient.

FIG. 19 shows the distal end of the device of FIGS. 13-18 with theengaging element expanded.

FIG. 20 shows the distal end of the device of FIGS. 13-18 with theengaging element collapsed.

FIG. 21 shows another device for removing an obstruction.

FIG. 22 shows the device of FIG. 21 expanded within a blood vessel.

FIG. 23 shows another device for removing an obstruction in a collapsedposition.

FIG. 24 shows one possible configuration for the expanded device of FIG.23.

FIG. 25 shows another possible configuration for the expanded device ofFIG. 23.

FIG. 26 shows a device having more strands and loops along the proximalsection than along the distal section.

FIG. 27 shows the device having an interlocking strand extending betweentwo strand loops.

FIG. 28 shows the strand loops interlocking closer to the distal andproximal ends in the upper and lower parts, respectively.

FIG. 29 shows the strands positioned within the expanded shape of themain element.

FIG. 30 shows the device positioned proximate to an obstruction.

FIG. 31 shows the device advanced into and through the obstruction.

FIG. 32 shows expansion of part of the main element distal to theobstruction.

FIG. 33 shows expansion of part of the main element within theobstruction.

FIG. 34 illustrates that rotation of the main element causes the strandto become entangled with the main element and enhances engagementbetween the device and the obstruction.

FIG. 35 shows still another device for removing an obstruction collapsedwithin the delivery catheter.

FIG. 36 shows the device in an expanded shape.

FIG. 37 shows the device of FIG. 35 with the filaments removed forclarity.

FIG. 38 shows the device of FIG. 36 with the filaments removed forclarity.

FIG. 39 shows still another device for removing an obstruction with acatheter having an interlocking structure.

FIG. 40 shows the interlocking structure entangled with an obstructionengaging element.

FIG. 41 shows the interlocking structure and element embedded within theobstruction.

FIG. 42 shows the interlocking structure and element being withdrawn.

FIG. 43 shows a catheter having a flexible tube to contain theobstruction.

FIG. 44 shows the obstruction contained within the catheter of FIG. 43.

FIG. 45 shows another catheter having a flexible tube which cooperateswith the element to dislodge and capture the obstruction.

FIG. 46 shows the catheter and element entangled.

FIG. 47 shows still another device for removing an obstruction.

FIG. 48 shows the device of FIG. 47 with the delivery catheterintroduced through the obstruction.

FIG. 49 shows the catheter retracted to expose the expandable portion ofthe element.

FIG. 50 shows the device being pulled proximally so that filamentscoupled to the expandable portion are tensioned to prevent excessiveelongation.

FIG. 51 shows still another device which has a stop to prevent distaldisplacement of the obstruction removing element.

FIG. 52 shows the device of FIG. 51 with the element expanded so thatthe obstruction engaging element contacts the stop on the insertionelement.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to FIGS. 1-4, a system 2 for removing an obstruction isshown. A guide catheter 4 is advanced to a location proximal to anobstruction. When accessing the cerebral vasculature, for example, theguide catheter 4 is often positioned in the carotid or vertebral artery.Of course, the guide catheter 4 may not be necessary or may bepositioned in any other suitable location depending upon the location ofthe obstruction. The guide catheter 4 preferably has a flow restrictingelement 6 which restricts or even stops blood flow through the vessel asdescribed below. The flow restricting element 6 is preferably a balloon5 coupled to a source of inflation fluid 7 which is used to inflate theballoon 5.

An obstruction removing device 8 is advanced through the guide catheter4 to the obstruction. A microcatheter 10 may also be positioned withinthe guide catheter 4 to deliver the obstruction removing device 8further into the vasculature. The obstruction removing device may beadvanced by itself through the microcatheter 10 or may be containedwithin a sheath 12 which is advanced through the microcatheter 10. Asource power 14 may also be coupled to the obstruction removal device 8for use in the manner explained below. The power source 14 may simplyproduce a positive or negative charge or may be an RF or other suitablepower source.

The obstruction removing device 8 has an engaging element 16 extendingfrom an insertion element 18. The engaging element 16 is movable from acollapsed position (FIG. 2) to an expanded position (FIGS. 3 and 4).When the engaging element 16 is contained within the sheath 12 ormicrocatheter 10, the engaging element 16 is in a relatively straightconfiguration. The engaging element 16 has a distal portion 20, whichforms a relatively closed structure, which can catch or trap theobstruction, or any part thereof, to prevent migration of theobstruction or part thereof. The engaging element 16 has a proximalportion 22 which is formed with smaller coils than the distal portion20. The proximal portion 22 engages the obstruction as described below.

The engaging element 16 (FIGS. 2-4) preferably has a number of markers23, 25, 27 (FIG. 1) which provide an indication as to how much of theengaging element 16 extends from the sheath 12 or microcatheter 10. Forexample, markers 23, 25, 27 may indicate when the engaging element 16 isabout to be exposed or is ½, ¾ or fully exposed. In this manner, theuser may quickly advance the engaging element engaging element 16through the sheath 12 or microcatheter 10 without inadvertently exposingand advancing the engaging element 16 out of the sheath 12 ormicrocatheter. The markers 23, 25, 27 can also be used to provide acontrolled diameter of the engaging element 16 since the diameter of theengaging element 16 is known for the various positions corresponding tothe markers 23, 25, 27. The markers 23, 25, 27 may also be used to sizethe vessel in which the engaging element 16 is positioned by observingwhen the engaging element 16 engages the vessel walls and determiningthe size of the engaging element 16 using the markers 23, 25, 27.

The insertion element 18 is preferably made of a superelastic materialor stainless steel having a diameter of 0.004 to 0.038 inch andpreferably about 0.010 inch. Although the insertion element 18 ispreferably a solid, elongate element, the insertion element 18 may takeany other suitable structure such as a hollow tube. The engaging element16 is preferably made of a superelastic material, such as nitinol, andhas a diameter of 0.005-0.018 inch, more preferably 0.005-0.010 inch andmost preferably about 0.008 inch. The engaging element 16 has a rounded,atraumatic tip 24 to prevent damage to the vessel and facilitateadvancement through the vessel, microcatheter 10 and/or sheath 12. Aradiopaque wire 26, such as platinum ribbon 28 having a width of 0.004inch and a thickness of 0.002 inch, is preferably wrapped around theengaging element 16 to improve radiopacity.

The device 8 is preferably self-expanding but may also be expanded withan actuator 29. The actuator 29 is preferably a thin filament which istensioned to move the device 8 to the expanded position. An advantage ofthe invention is that the filament 29 extends through the same lumen asthe device 8 thereby minimizing the overall size of the device. It isunderstood that throughout discussion of the devices and methods hereinthat any of the devices may be expanded using the actuator 29 ratherthan being self-expanding without departing from the scope of variousaspects of the invention.

The device 8 may also include a cover 9 which extends between adjacentcoils. The cover 9 may be a number of individual strands 11 which extendbetween the coils or may be an elastic membrane which covers the coils.The strands 11 are preferably elastic to stretch when the device 8 isexpanded.

Use of the obstruction removing device 8 is now described. The guidecatheter 4 is introduced into the patient and delivered proximal to thetarget vessel such as to the carotid or vertebral artery. Themicrocatheter 10 is then advanced through the guide catheter 4 furtherinto the vasculature to a position proximal to, within or distal to theobstruction. The obstruction removal device 8 is then advanced throughthe microcatheter 10 either by itself or pre-loaded within the sheath12. The obstruction removal device 8 is then advanced to theobstruction. Before advancing the obstruction removal device 8 further,the flow restricting element 6 on the guide catheter 4 is expanded toreduce and even stop flow through the vessel. Stopping flow in thevessel may help prevent the obstruction, or any parts thereof, frommigrating downstream. Reducing flow through the vessel may also reducethe likelihood that the obstruction is disrupted by a combination offlow and the obstruction removal device 8.

The obstruction removal device 8 is then placed into the obstruction andpreferably through the obstruction. The engaging element 16 is thenadvanced out of the microcatheter 10 or sheath 12 to permit the distalportion 20 of the engaging element 16 to expand at a location beyond theobstruction. In this manner, the relatively closed distal portion 20prevents the obstruction, or any part thereof, from migratingdownstream. The proximal portion 22 is then advanced out of the sheath12 or microcatheter 10 so that the smaller coils of the proximal portion22 engage the obstruction as shown in FIG. 4.

The power source 14 may be also be used with any of the obstructionremoval devices in the following manner, however, the methods anddevices of the present invention may, of course, be practiced withoutthe power source 14. As mentioned above, the power source 14 may simplyproduce a charge at the engaging element 16 or may be a source of RFenergy. In one particular method of the present invention, the powersource 14 produces a negative charge while advancing the engagingelement 16 through the obstruction. The negative charge may aid inpassing the engaging element 16 through the obstruction and may help todissolve part of the obstruction. The power supply is then changed toproduce a positive charge to adhere the obstruction to the engagingelement 16. Alternatively, the power source 14 may be an RF energysource, which delivers RF to the engaging element 16 which also adheresthe obstruction to the engaging element 16 and may help provide acontrolled penetration into the obstruction. The obstruction is thenremoved by moving the obstruction into the guide catheter 4, which isthen withdrawn to remove the obstruction. Use of the power source 14 isparticularly useful when the obstruction is a biologic structure such asa clot.

Referring to FIG. 6, a capture element 150 is shown. The capture element150 has a cover 114 and an actuator 138 which includes a stable arm 142,a control arm 140, and a loop 136 although other actuating structuresmay be used. The capture element 150 is contained within the catheter107 or the guide catheter 4 during introduction and is then everted outof the catheter 107 or catheter 4 when deployed. After the obstructionis contained within the capture element 150, the capture element 150 iswithdrawn into the catheter 4. Although it is preferred to withdraw thecapture element 150 into the catheter 4, the capture element 150 may becollapsed and then inverted back into the catheter 134 thereby trappingthe obstruction in the catheter 134 itself.

The capture element 150 is opened and closed by manipulating the arms140, 142 to open and close the loop 136. The obstruction is capturedwith the element 150 by itself or together with an obstruction engagingelement as described herein

Referring to FIGS. 7-12, another capture element 200 is shown forcapturing an obstruction. The capture element 200 has an invertingportion 202 that inverts to entrap the obstruction. The capture element200 is then withdrawn into the guide catheter 4 (FIG. 1) for removal ofthe obstruction from the patient.

Referring to FIG. 10, the engaging element 204 is shown engaging theobstruction. The element 204 may be any suitable element such as theobstruction engaging elements and removal devices described herein. Theelement 204 passes through a lumen 205 in the capture element 200. Theengaging element 204 may be advanced through the capture element 200 byitself or may be contained within the microcatheter 10 or sheath 12(FIGS. 1 and 2) which is advanced through the capture element 200.

The capture element 200 has a distal portion 207 which is flexible andwhich may be partially contained, engaged or otherwise in contact withthe obstruction as shown in FIG. 8. The distal portion 207 may alsoinvert but preferably does not invert. The distal portion 207 necks-downat a distal end 209 to a size smaller than the guidewire GW so that thecapture element 200 is advanced together with the guidewire. Of course,the capture element 200 may also be advanced by itself afterintroduction of the guidewire and may be contained within or advancedover another catheter without departing from the invention.

The element 204 engages the obstruction in any suitable manner. Theinverting portion 202 is then inverted by applying a compressive forceto the inverting portion 202. The compressive force is applied by movingthe capture element 200 relative to the engaging element 204 whichcauses the element 200 and/or obstruction to compress the invertingportion. Continued relative movement moves the obstruction into theinverted capture element 200 as shown in FIGS. 11 and 12 to capture theobstruction. The capture element 200 is then moved into the guidecatheter 4 (FIG. 1) for removal from the patient. The capture element200 may be made of any suitable materials. For example, the distalportion 207 may be made of any suitable polymeric material such as thosedescribed herein and the inverting portion 202 may be made of a braidedor woven material or fabric made of fibers or filaments of nitinol,stainless steel, polymer or other material.

Referring to FIGS. 13-20, another capture element 210 for removing anobstruction is shown wherein the same or similar reference numbers referto the same or similar structure. The capture element 210 also has aninverting portion 212 connected to an end 213 of a delivery element 214which may be a hollow tube, sheath or catheter. The distal end of thecapture element 210 has a collar 214 attached to a proximal end 216 ofan engaging element 218. A distal end 220 of the obstruction engagingelement 218 is attached to an inner element 222 such as a wire, mandrelor guidewire. The collar 214 slides over the inner element 222 so thatwhen the inner element 222 and delivery element 214 are movable relativeto one another. Relative movement between the inner element 222 anddelivery element 214 moves the obstruction engaging element 218 betweenthe expanded and collapsed positions (FIGS. 19 and 20) and also cancollapse the capture element 210. The engaging element 218 is similar tothe other elements and devices described herein in that the element hasa filament 224 which is tensioned to collapse the filament 224. Thefilament 224 forms coils 226 around the inner element 222.

The capture element 210 and obstruction engaging element 218 areadvanced through the patient in either the sheath 12 or microcatheter 10(FIGS. 1 and 2). The capture element 210 and obstruction engagingelement 218 are then positioned distal to the obstruction and theobstruction is engaged with the element 218. The capture element 210 andengaging element 218 are then moved relative to one another to invertthe capture element 210 as described above.

Referring to FIGS. 21-29, still another device 902 for removing anobstruction is shown. The device 902 has a main element 904 that may beany suitable element 904 such as those described herein. The element 904is held in a substantially straight, collapsed position within thedelivery catheter 905 as described above. Similar to the embodiment ofFIGS. 2 and 3, the element 904 has one or more strands 906 which extendalong the element 904. Of course, the strands 906 may extend freelyalongside the main element 904 or may be wound helically, interwoven orinterlocked with the element 904 without departing from the scope of theinvention. The strands 906 are tied, knotted, looped, soldered, orotherwise attached to the main element 904 at the ends of the expandableportion of the main element 904. Of course, the strands 906 may belooped around or attached to the main element 904 at other parts of themain element 904. For example, the strand 906 may be attached or coupledto the main element 904 several centimeters proximal to the expandableportion of the main element 904 without departing from the scope of theinvention.

The main element 904 may be any suitable element 904 which is naturallybiased toward the expanded position such as any of the elementsdescribed herein. FIGS. 22, 24 and 25 show three different embodimentsof the main element 904 for purposes of illustration. The main element904 may form helical coils 907 having varying diameter as shown in FIG.22 or may have coils 907 with the same diameter as shown in FIG. 25 ormay even have coils 907 which extend transverse to the longitudinal axisas shown in FIG. 24. Of course, any suitable shape may be used for themain element 904. Any of the devices described herein may have a mainelement which extends transverse or perpendicular to the longitudinalaxis as shown in FIG. 24 and as further shown below in connection withFIG. 36. Thus, the embodiment of FIG. 29, for example, may have thecoils extending transverse to the longitudinal axis.

The strand 906 may be any suitable filament, wire, fiber, monofilamentand may be made of any suitable material such as nylon, polypropylene,polyester, polyurethane, silicone, latex, a liquid crystal polymer (LCP)such as Vectran or even nitinol or stainless steel. The strand 906 isflexible and may or may not have a predetermined shape with the strand906 being deformed and deflected by the element 904 as the element 904expands. The element 904 includes two strands 906 which interlock orhave interlocking loops 908 at about the midpoint of the expandableportion of the element 904. Stated another way, the strands 906 form twoloops 908 which interlock at the midpoint as shown in FIG. 21. Thestrands 906 and loops 908 are shown in an exaggerated state in thecollapsed position of FIG. 21 for clarity. Of course, one advantage ofthe invention is that the strands 906 are relatively small and flexibleand do not take up much space in the lumen of the delivery catheter ascompared to conventional structures using wires and the like. Thisfeature cannot be appreciated, of course, in the exaggerated depictionof FIG. 21.

Referring to FIG. 26, the strands 906 may also form more loops 908 onone side than on the other. An interlocking loop 910 extending aroundthe main element 904 may also be provided to interlock pairs of loops908 as shown in FIG. 27. The strands 906 or loops 908 may also intersectnearer to the proximal or distal ends as shown in the upper and lowerparts of FIG. 28. Referring to FIG. 29, the strands 906 may also bepositioned generally inside the element 904 when the element 904 isexpanded. The device may be loaded by pulling the ends of the element904 when in the position of FIG. 25 to collapse the main element 904around the strands 906. The device is then restrained in the deliverycatheter 905 and delivered to the obstruction.

Referring again to FIGS. 22-25, the main element 904 may have a filament912, such as platinum coil, wound around the expandable portion of themain element 904. The filament may help to improve radiopacity and mayalso be sized and configured so that the strand 906 can be held betweenadjacent windings of the filament 912 to enhance interlocking engagementbetween the strand 906 and element 904. Alternatively, the filament 912may only be provided at the ends of the expandable portion of the mainelement 904 as shown in FIG. 22 where the strands 906 are coupled to themain element 904.

Use of the devices 902 of FIGS. 21-29 is now described with furtherreference to FIGS. 30-34. The delivery catheter 905 is passed throughthe obstruction so that the distal tip is beyond the obstruction asshown in FIG. 31. The main element 904 is then expanded so that one ormore coils are distal to the obstruction as shown in FIG. 32. Thedelivery catheter 905 is then withdrawn further to expose more of theexpandable portion of the main element 904 as shown in FIG. 33. Althoughit is preferred to position one or more coils distal to the obstruction,all or part of the expandable portion of the main element 904 may beexpanded within, distal or even proximal to the obstruction withoutdeparting from the scope of the invention.

The device 900 may emerge from the delivery catheter 905 with thestrands 906 being relatively free of the main element 904 between theproximal and distal attachments to the main element. Of course, thestrands 906 may be interwoven, looped around or even somewhat entangledwith the main element 904 so long as the user may manipulate the deviceto further entangle the strand 906 and element 904. Rotation of thedevice causes the strands 906 to become entangled with the main element904 in a manner dictated by the geometric restrictions of the vessel andobstruction. The device itself may also become more entangled with theobstruction during rotation of the main element 904. An advantage ofusing the helical or coiled structures described herein is that rotationof the main element 904 not only causes the device to engage theobstruction but also causes the strand 906 to become entangled with themain element 904.

Another aspect of the present invention is that the amount ofentanglement between the strand 906 and element 904 may be controlled.For example, the user may first attempt to remove the obstruction withlittle or no rotational manipulation of the element 904. The user canthen pull on the main element 904 and determine whether the device canremove or dislodge the obstruction or whether the main element isdisengaging or slipping relative to the obstruction. Disengagement canoccur due to excessive elongation or distortion of the main element 904or may be simply due to poor engagement between the device andobstruction. The user may then rotate or otherwise manipulate the deviceto cause further entanglement between the strand 906 and element 904 andbetween the device itself and the obstruction. Increasing theentanglement between the strand 906 and main element 904 may help toreinforce the main element which can reduce stretching and distortion ofthe main element 904 when the main element 904 is tensioned. The strands906 also increase the overall surface area of the device and generallyreduce the size of interstitial spaces in the main element 904. Anotheraspect of the present invention is that the strand 906 and element 904may engage one another at locations dependent upon the permittedexpansion of the main element 904 within the vessel. As such, thepresent invention provides advantages over conventional mesh-likestructures having a predetermined geometry since these structures maynot perform adequately under a variety of different size restrictions inan obstruction.

Although the strand 906 and element 904 may not be substantiallyentangled when the element is initially expanded, the main element 904and strand 906 may also be designed to become entangled with one anotherduring expansion of the main element 904. For example, the element 904may naturally begin to twist in a helical manner to form coils 908 whenexpanding due to the shape of the element 904. The twisting motioncauses the strand 906 to engage, contact and/or otherwise entangleitself with the element 904 and obstruction. The strand 906 will engagethe element 904 at a number of locations dependent upon the manner inwhich the element expands within the vessel as described above. Althoughthe element 904 generally follows a helical path when expanding, theelement 904 may expand in any other manner which tends to entangle thestrand 906 and element 904. For example, the element 904 may rotate oneway and then another or may be longitudinally displaced or reciprocated.Thus, it can be appreciated that the element may expand in a number ofdifferent ways to cause the strand 906 to become entangled with theelement. Of course, the element may also be rotated or otherwisemanipulated to enhance entanglement between the strand 906 and elementeven after expansion of the main element to provide the advantagesdescribed above.

After the obstruction has been engaged by the device, the main elementis pulled to dislodge the obstruction for removal as describe above.Once the element has dislodged the obstruction, the obstruction may bemoved into a guide catheter 909 or sheath for removal from the patient.The guide catheter 909 may have a balloon to occlude blood flow duringwithdrawal of the obstruction.

Referring now to FIGS. 35-38, still another device 300 for removing anobstruction from a vascular location is shown. The device 300 includes amain element 302 having a self-expanding portion 304 which forms anumber of coils 306. Of course, the element 302 may take other shapeswhen expanded such as those described herein and incorporated byreference. The coils 306 may be oriented at an angle of about 90 degreeswith respect to a longitudinal axis of the element 302 or may beoriented in any other manner such as parallel to the longitudinal axis.The coils 306 may have substantially the same diameter or the diameterof the coils 306 may vary in any suitable manner. The device 300 has oneor more filaments 308 extending alongside the coils 306 similar to otherdevices described herein such as the devices of FIGS. 1-4 and 21-34.FIGS. 37 and 38 show only the element 302 and catheter 309 for claritywhile FIGS. 35 and 36 show both the element 302 and filaments 308.

The filaments 308 are coupled to the main element 302 at proximal anddistal locations 310, 312. The filaments 308 may be coupled to theelement 302 at non-expanding portions just proximal and distal to theself-expanding portion 304 or the filaments 308 may be coupled to theexpanding portion 304 of the element 302 such as the coils 306. Thefilaments 308 are preferably free to slide at the proximal location andare looped around the main element 302 to permit sliding. The filaments308 are fixed at the distal location by securing the filaments 308between windings of a radiopaque wire wrapped around the main element302 at the distal end (see radiopaque wire 26 of FIG. 2). Other devicesdescribed herein, such as the devices of FIGS. 21-34, may have filamentswhich are slidable on the main element. For example, the wire 912 may beslidable on the main element so that all of the filaments 906 arecoupled together and slidable on the main element 904. Alternatively, ofcourse, the filaments may be independently slidable on the main elementby simply looping the filaments around the main element as describedabove.

Use of the device of FIGS. 35 and 36 is now briefly described and allmethods of using the devices described in connection with FIGS. 1-4 and21-34 are incorporated here. The guidewire (see FIG. 1) is initiallyadvanced through the obstruction and the catheter 309 is then advancedinto or through the obstruction over the guidewire. The self-expandingportion 304 is then permitted to expand by either advancing the elementor retracting the catheter 309. The expanding portion 304 of the mainelement 302 may be deployed distal to the obstruction or may bepartially or entirely deployed within the obstruction. As the element302 and filaments 308 are deployed, the element 302 and filaments 308interact with one another and with the obstruction as the element 302expands. The manner in which the filaments 308 deploy and contact themain element 302 and obstruction is dependent upon various factorsincluding the geometry of the vessel and obstruction and the manner inwhich the element 302 expands as explained above. The filaments 308 mayprevent excessive elongation of the main element 302 and may improve theability of the element 302 to capture the obstruction.

Referring now to FIGS. 39-42, still another system 400 is shown forremoving obstructions from a vascular location. The system includes anobstruction engaging element 402 which works together with a catheter404 to remove the obstruction. The element 402 is preferably advancedthrough a lumen 406 in the catheter 404 as described below. The element402 has an expanding portion 405 which expands to form coils 407 asdescribed herein. The element 402 may be any suitable element 402 whichis configured to engage the obstruction such as those described herein.

The catheter 404 has an interlocking structure 410 at the distal endwhich cooperates with the element 402 to dislodge and remove theobstruction or may be used by itself to engage, dislodge and remove theobstruction. The interlocking structure 410 is preferably a loose,flexible structure formed by flexible filaments 408 such as suture orwire. The filaments 408 are attached to the distal end of the catheter404 and may form loops 412 or may be woven or interlocked in any manner.The catheter 404 has eight loops 412 attached to the distal end of thecatheter 404 with the loops 412 having two different sizes. A radiopaquematerial 414, such as platinum, may be attached to the filaments 408 atdiscrete locations to improve radiopacity and to improve the ability ofthe interlocking structure 410 to become entangled with the element 402and obstruction. The material 414 may be formed in any suitable mannersuch as beads of platinum or small coils or tubes attached to thefilaments 408.

The relatively flexible nature of the filaments 408 does notsubstantially increase the stiffness of the catheter 404 so that thecatheter 404 can still be advanced through small and tortuous vessels.As the catheter 404 is advanced through the patient's vasculature, thefilaments 408 are free to move and displace and will naturally lieagainst the body of the catheter 404. The catheter 404 may be deliveredthrough another catheter, such as a guide catheter, which is advanced toa location near the obstruction with the catheter 404 being advanced byitself over the guidewire to the obstruction (see FIG. 1). The catheter404 may even be used by itself to remove an obstruction or may be usedwith another catheter which encapsulates the obstruction such as thedevice of FIGS. 43 and 44 described below.

Another method of the present invention is now described with referenceto the system of FIGS. 39-42. The guidewire (see FIG. 1) is advancedthrough the obstruction and the catheter is then advanced through theobstruction over the guidewire. The catheter 404 is then withdrawn asmall distance so that the interlocking structure 410 is deployed distalto the obstruction. The guidewire is then withdrawn and replaced by theelement 402. The element 402 is then permitted to expand by advancingthe element 402 or withdrawing the catheter 404 to expose the element402. Exposure of the element 402 may cause the element 402 andinterlocking structure 410 to naturally become entangled or interlocked.The element 402 may also be twisted or rotated to enhance interactionbetween the interlocking structure 410 and element 402. The catheter 404and element 402 are then moved proximally to engage and dislodge theobstruction. Although the entire interlocking structure 410 andexpanding portion 405 of the element 402 are shown distal to theobstruction, part of either structure may, of course, be deployed withinthe obstruction. For example, with reference to FIGS. 40 and 41, thecatheter 404 may be advanced into or through the obstruction and thenwithdrawn into the obstruction so that the loose, flexible filaments 408are naturally left within the obstruction. The element 402 is thendeployed within the obstruction and the element 402 is manipulated toentangle the element and filaments 408. Of course, some part of theelement, such as a few windings of the coil 407, may be deployed distalto the obstruction before withdrawing the catheter 404. After theelement 402 and interlocking structure 410 have become entangled, theelement 402 is manipulated to dislodge and remove the obstruction.

Referring to FIGS. 43 and 44, still another system 500 for removing anobstruction is shown. The system 500 includes an obstruction engagingelement 502 which may be any suitable element such as those describedherein. The system 500 also includes a catheter 504 which receives andcontains the obstruction during removal from the patient. The catheter504 has a containment chamber 506 which is defined by a flexible tube508. The tube 508 may be everted from the position of FIG. 42 to theposition of FIG. 43. The tube 508 is made of expanded PTFE but may bemade of any other suitable material.

In use, the obstruction engaging element 502 engages the obstruction andthe catheter 504 is advanced adjacent to the obstruction as shown inFIG. 43. The catheter 504 and element 502 are then moved proximallytogether so that the containment chamber 506 everts and covers theobstruction. The catheter 504 and element 502 are then withdrawn fromthe patient together to remove the obstruction. The flexible containmentchamber 506 protects and encases the obstruction to reduce thelikelihood of losing pieces of the obstruction as the obstruction isremoved.

Referring to FIGS. 45 and 46, still another device 600 for removing anobstruction is shown. The device 600 includes a catheter 602 having atube 604 mounted to the distal end. The tube 604 has openings 606therein such as longitudinal slots 608. The device 600 is similar toother devices described herein in that the tube 604 cooperates with anelement 610 to dislodge and remove an obstruction. The element 610 ismanipulated so that the element 610 extends through one or more of theopenings 606 to entangle the element 610 and tube 604. The tube 604 maybe deployed distal to the obstruction by advancing the catheter 602through the obstruction and then withdrawing the catheter 602 to deploythe tube 604. The element 610 is then advanced out of the distal end ofthe catheter 602 and manipulated to entangle the tube 604 and element610 together. For example, the element 610 may be twisted and/or pulledproximally. Of course, the element 610 may naturally twist or displaceto pass through the openings 606 when advanced from the catheter 602.

Referring now to FIGS. 47-50, still another device 700 for removing anobstruction from a blood vessel is shown wherein the same or similarreference numbers refer to the same or similar structure. An obstructionengaging element 702 has an expandable portion 704 which expands to forma helical coil 706. The element 702 may take any other suitable shapewithout departing from various aspects of the present invention,however, the helical or coiled shape may have some advantages over othershapes. For example, the coiled or helical shape may improve the abilityto rotate the element 702 into engagement with the obstruction. Theexpandable portion 704 has a proximal end 708 slidably mounted on aninsertion element 710. The proximal end 708 may form a coil 709 whichcan slide along the insertion element 710 to permit the element 702 toexpand. A tether 711 may be used to collapse the element 702 by simplypulling on the tethet 711. The proximal end 708 may also pivot or rotateon the insertion element to provide added flexiblity to the system. Adistal end 712 of the expandable portion 704 is attached to theinsertion element 710 near the distal end of the insertion element 710.The distal end 712 may have a collar 713 which allows the distal end 712to pivot or rotate on the insertion element to provide the element 702with added flexiblity and also permits the element 702 to changeorientation with respect to the insertion element 710. The distal end712 may also be permitted to displace longitudinally relative on theinsertion element 710 a limited amount by permitting movement of thecollar 713 on the insertion element 710 between first and second stops715, 717.

Similar to other embodiments described herein, the device 700 has one ormore filaments 714 which help prevent the element 702 from beingexcessively distorted when the element 702 is pulled proximally orotherwise manipulated. Any number of filaments 714 may be used with theembodiment of FIGS. 47-50 having two filaments 714 positioned onopposing sides of the expandable portion 704. Similar to otherembodiments described herein, the filament 714 has a proximal endcoupled to the insertion element 710. The filament 714 is coupled to aproximal winding 724 of the helical coil 706. The filaments 714 aresized and positioned so one or both filaments 714 can exert tension onthe proximal winding 724 when the insertion element 710 is pulledproximally as shown in FIG. 50. Of course, the filament 714 may becoupled to other parts of the element 702 and, in particular, otherparts of the expandable portion 704 without departing from the scope ofthe invention.

The filament 714 may be made of any suitable material includingpolymeric or metallic materials such as nylon, polypropylene, platinum,nitinol or stainless steel. The filament 714 is flexible and preferablydoes not have any particular predetermined shape although parts or evenall of the filament 714 may be shaped without departing from the scopeof the invention. As such, the filament 714 is essentially displaced bythe obstruction engaging element 702 when the element 702 expands. Thefilament 714 may be one or more strands of suture 721, a polymer braidor monofilament, or stranded or twisted braid or monofilament. Thesuture 721 may be coupled to the element 702 in any suitable manner. Forexample, a platinum wire may be used to form a coil 723 around theelement 702. The sutures 721 are then positioned within the coil 723 andare trapped between the coil 723 and the element 702. A number offilaments 714, such as sutures, may run through the coil. Of course, thefilament 714 may be coupled to the expandable portion 704 in any othersuitable manner. For example, the filament 714 may be attached to theinsertion element at the proximal end and slidably coupled to theexpandable portion 704 at the distal end 725 as described above. Thedistal end 725 may use any suitable connection so that the filament 714can slide along the element 702. For example, the filament may simply bewrapped or looped around the element 702. The proximal end of thefilaments 714 may also be coupled to a collar 720 which permits theproximal end of the filaments 714 to slide and rotate on the insertionelement 710. A stop 727 may be mounted on insertion element 710 toprevent distal movement of the proximal end of the filaments 714 beyondthe stop 727. Of course, the proximal and distal ends of the filament714 may also be rigidly attached to the element 702 or may be attachedin a manner that prevents sliding without departing from numerousaspects of the invention.

Similar to other embodiments described herein, the filament 714 helps toinhibit or prevent distal movement or displacement of the expandableportion 704 relative to the insertion element 710 when the device 700 ispulled proximally or otherwise manipulated to engage, dislodge or movethe obstruction. Of course, the proximal force on the element 710 may becreated by simply pulling on the element 710 or by even rotating theelement 710 which can also produce tension on the element 710. After theelement 702 has been released and expanded within the body, the element702 is manipulated to engage, ensnare, dislodge and move the obstructionand pulled proximally which tends to stretch, elongate or straighten theelement 702. Straightening of the element 702 may result in the element702 simply pulling through the obstruction without dislodging or movingthe obstruction. The filaments 714 may help prevent excessive distortionor elongation of the element 702 and may also provide additionalstructure to help engage, dislodge and capture the obstruction.

Use of the device 700 is now described with reference to FIGS. 47-50.The device 700 is positioned within a catheter or delivery sheath 730 tosubstantially straighten the expandable portion 704 of the device 700.The expandable portion 704 and catheter 730 are exaggerated for clarity.The catheter or delivery sheath 730 is advanced through the obstructionand the device 700 is positioned near the distal end of the catheter730. Of course, the device 700 could be introduced through theobstruction in some other manner without departing from numerous aspectsof the present invention. The catheter 730 is then withdrawn, and/or thedevice 700 is advanced, so that the expandable portion 704 of theelement 702 is partially deployed distal to the obstruction andpartially deployed within the obstruction. Of course, the expandableportion of the element 702 may be deployed entirely distal to theobstruction, partially within the obstruction and partially distal tothe obstruction, or entirely within the obstruction without departingfrom numerous aspects of the invention. When the element 702 isdeployed, the expandable portion 704 naturally expands toward theexpanded position. When the user begins to manipulate the element 702 bymanipulating the insertion element 710, the obstruction begins to becomeentangled or ensnared by the element 702. The element 702 may be rotatedor simply pulled proximally to engage and dislodge the obstruction. Whenthe user pulls proximally on the element 710, the expandable portion 704of the element 702 may tend to stretch, however, the filaments 714 mayhelp prevent excessive distortion or elongation of the expandableportion 704. Referring to FIG. 50, for example, the filaments 714 areshown in tension as the device 700 is pulled proximally. The filaments714 prevent excessive elongation or distortion of the expandable portion704 and, in particular, the proximal windings of the helical coil 706.After the obstruction has been dislodged, the obstruction is removed inany manner described herein or any other suitable manner such as movingthe obstruction into a guide catheter for removal. The element 702 maybe collapsed using a catheter such as the catheter 730 by simply movingthe element 702 into the catheter by advancing the catheter 730 and/orwithdrawing the element 702 into the catheter 730.

Referring now to FIGS. 51 and 52, still another device 280 for removingan obstruction is shown. The device 280 may be used in any suitablemanner described herein. For example, the device 280 may be advanced byitself or advanced while contained in a sheath or catheter. The sheathor catheter 281 holds the device 280 in a substantially straightconfiguration. The device 280 has an elongate element 282, such as awire 284, which expands to the expanded shape of FIG. 52 similar toother embodiments described herein. The elongate element 282 has adistal end 286 coupled to an insertion element 288. A proximal end 290of the elongate element 282 is coupled to a collar 292, which slides onthe insertion element 288. Sliding of the collar 292 permits theelongate element 282 to move between the collapsed and expandedpositions of FIGS. 51 and 52. The insertion element 288 also has a stop294, which prevents movement of the collar 292 beyond the position ofFIG. 52. The device 280 may also have a pull wire 289. The pull wire 289may not be needed to hold the element 282 in the collapsed positionsince the catheter 281 may be used to hold the element in the collapsedposition 282. The pull wire 289 gives the user the ability to collapsethe element 282 if needed after deployment. The element 282 may, ofcourse, take other shapes such as a double-helix which would include thedotted-line structure as well.

Referring again to FIGS. 49 and 50, the obstruction removing device 700may also include a releasable connection 740. The releasable connection740 is released to change the characteristics of the device 700 and maybe particularly useful for changing the nature of the device after thedevice has already been introduced into the patient. The releasableconnection 740 may release an end of the filament 714 in any suitablemanner such as an electrolytic connection 742. Alternatively, thefilament 714 may simply be looped around a structure and released byreleasing one end and pulling on the other end. Of course, theconnection 740 may also be positioned on other parts of the device otherthan the filament 714 without departing from the present invention suchas at the collar 720 at the proximal end of the filaments 714.

The releasable connection 740 may be released by the user at any timedeemed appropriate by the user to change the characteristics of thedevice 700. For example, the user may wish to prevent transmittingexcessive force with the device 700 to the obstruction or vasculature.These concerns are particularly relevant when working in small, tortuousand/or delicate vessels in the brain. Thus, it may be desirable to limitthe transmission of high forces to the obstruction by reducing theoverall ability of the device to engage and ensnare the obstruction. Tothis end, the releasable connection 740 may serve to reduce tensileforces exerted by device 700 when engaging the obstruction. For example,the filament 714 may be in tension when the user is manipulating thedevice 700 to engage the obstruction. Releasing the filament 714 maytend to reduce the forces being transmitted to the obstruction by thedevice.

Releasing one or more parts of the device 700 may also tend to reducethe interlocking nature of the device 700. The releasable connection 740may, in fact, be used for the express purpose of disengaging the device700 from the obstruction when the user is not comfortable with theprogression of the procedure or the level of force which is apparentlyrequired to dislodge or move the obstruction. Thus, the releasableconnection 740 provides the user with the ability to disengage thedevice from the obstruction and, if desired, remove the device 700without removing the obstruction. Alternatively, the releasableconnection 740 may simply reduce the ability of the device 700 to exerthigh forces on the obstruction or may be used to partially disengagefrom the obstruction as desired by the user. The device 700 may have anumber of releasable connections 740. The releasable connections 740 maybe released one at a time so that the user may select the desiredcharacteristics or release the connections 740 individually as desired.As discussed above, the element 702 may also be collapsed using acatheter such as the catheter 730 by simply moving the element 702 intothe catheter by advancing the catheter 730 and/or withdrawing theelement 702 into the catheter 730.

It is understood that the releasable connection 740 may be provided inany of the devices described herein and discussion of the uses andadvantages of the releasable connection are equally applicable for anyof the devices described herein. Examples of the releasable connection740 are also shown in FIGS. 4, 22, 25, 27 and 36 and all uses of theconnection 740 are equally applicable to those devices shown.Furthermore, all disclosure related to these embodiments is incorporatedhere including all claims and disclosure in the related applications andapplications incorporated by reference. For example, the device 8 ofFIG. 4 may be used in the manner described but with use of thereleasable connection 740 at the desired time. The releasable connection740 in FIG. 4 may be used to release one or more of the strands 9 whichin turn may release part of the obstruction engaging portion 16.Referring to FIG. 27, the releasable connection 740 may be provided atthe looped portion 908 of the strand 906 so that other strands 906 orloops 908 are released.

Although the connection 740 described above may be released by the userat the desired time, the releasable connection 740 may alsoautomatically release upon a predetermined threshold force. For example,the releasable connection 740 may break at a predetermined tension. Thereleasable connection may be designed to break upon a tensile load ofless than 5 lbs, or even less than 2 lbs. An advantage of such a systemis that the forces exerted on and by the device 700 may be used todetermine release of the connection 740 as opposed to the forcesrequired to manipulate the device from the proximal end. As can beappreciated, the amount of force at the proximal end may differ greatlyfrom the forces being exerted by or on the device.

While the above is a description of the preferred embodiments of theinvention, various alternatives, substitutions and modifications may bemade without departing from the scope thereof, which is defined by thefollowing claims. Thus, the preferred embodiments should not be taken aslimiting the scope of the invention. For example, although all of theobstruction removal devices described herein are self-expandingstructures, the obstruction removal devices may also have actuatingmechanisms for moving the engaging element between the expanded andcollapsed positions. Furthermore, the present invention is directed to anumber of separate inventions and each of these inventions may beclaimed independently of one another. Each feature, aspect and advantageof the invention may be claimed independent of one another withoutdeparting from the scope of the invention. As a further example, anyengaging device, even a balloon, may be used with some of the inventiveaspects of the capture element and any capture element may be used withinventive aspects of the engaging device. Finally, the devices of thepresent invention may also be used in connection with simply controllingblood flow through an area and not necessarily with removal of anobstruction.

1. A method of removing an obstruction from a patient, comprising thesteps of: providing an obstruction removing device having an obstructionengaging portion movable from a collapsed position to an expandedposition, the obstruction removing device also having a releasableconnection; introducing the obstruction removing device into a patientin the collapsed position; engaging an obstruction with the obstructionengaging portion, the releasable connection being intact during theengaging step; releasing the releasable connection of the obstructionengaging device after the engaging step, the releasing step releasing aconnection in the obstruction removing device thereby reducing thenumber of interconnections in the device.
 2. The method of claim 1,wherein: the releasing step is carried out with the releasableconnection being an elongate element.
 3. The method of claim 1, wherein:the releasing step is carried out with the releasable connection beingin tension during the engaging step.
 4. The method of claim 1, wherein:the releasing step is carried out with the releasable connection beingin tension prior to release.
 5. The method of claim 1, wherein: thereleasing step is carried out with the releasable connection being anelectrolytically severable bond.
 6. The method of claim 1, wherein: thereleasing step reduces the engagement between the device and theobstruction.
 7. The method of claim 1, further comprising the step of:disengaging from the obstruction after the moving step; and removing thedevice from the patient without removing the obstruction with thedevice.
 8. The method of claim 1, wherein: the releasing step is carriedout with the releasable connection automatically releasing.
 9. Themethod of claim 8, wherein: the releasing step is carried out with uponapplication of a threshold force of less than five lbs.
 10. The methodof claim 1, wherein: the providing step is carried out with theobstruction engaging portion being naturally biased toward the expandedposition.
 11. The method of claim 1, further comprising the step of:releasing another releasable connection on the obstruction removingdevice.
 12. The method of claim 1, wherein: the providing step iscarried out with the releasable connection being part of a flexiblefilament having no predetermined shape.
 13. The method of claim 1,wherein: the providing step is carried out with the releasableconnection being positioned along a loop of material; and the releasingstep eliminates the loop.
 14. An obstruction removing device,comprising: an obstruction engaging portion movable from a collapsedposition to an expanded position, the obstruction removing device alsohaving a releasable connection which is selectively releasable by theuser, the releasable connection being used to change a characteristic ofthe device inside the patient, the releasable connection releasing aconnection thereby reducing the number of interconnections in thedevice.
 15. The obstruction removing device of claim 14, wherein: thereleasable connection is a tension element.
 16. The obstruction removingdevice of claim 14, wherein: the releasable connection is a filament.17. The obstruction removing device of claim 14, wherein: the releasableconnection is configured to be in tension when engaging an obstructionso that the tension is reduced when the releasable connection isreleased.
 18. The obstruction removing device of claim 14, wherein: thereleasable connection automatically release at a threshold force. 19.The obstruction removing device of claim 18, wherein: the releasableconnection releases upon a threshold tensile load of less than five lbs.20. The obstruction removing device of claim 14, wherein: the releasableconnection has an electrolytically severable bond.
 21. The obstructionremoving device of claim 14, wherein: the releasable connection ispositioned along a loop of material, wherein releasing the releasableconnection eliminates the loop.
 22. The obstruction removing device ofclaim 14, wherein: the obstruction removing device includes a pluralityof releasable connections.
 23. The obstruction removing device of claim14, wherein: the obstruction engaging portion is naturally biased towardthe expanded position.
 24. An obstruction removing device, comprising:an obstruction engaging portion movable from a collapsed position to anexpanded position, the obstruction removing device also having aplurality of releasable connections which are each selectivelyreleasable by the user, the releasable connection being used to change acharacteristic of the device inside the patient, each of the releasableconnections releasing at least one connection thereby reducing thenumber of interconnections in the device.